At present, cremation is the main process for the disposal of large animal carcasses and is often used for the disposal of bodies of dead humans. The process uses large quantities of fossil fuels and results in the discharge of large volumes of carbon dioxide to the atmosphere. This clearly has negative environmental consequences in relation to atmospheric CO2. The other common method of disposal of such organic material is burial, and in the context of disposal of animal waste, often mass burial. This process has, however, possible negative consequences for soil contamination, and damage to watercourses, especially from mass animal burial sites.
Despite the high energy demand of the cremation process, burning of such animal remains has the advantage of killing any pathogens within the bodies, so preventing microbial contamination of the ground in which the ashes may be deposited. Such pathogens occur naturally in the digestive tract of animals, but particular pathogens may also be present in the material such as those that led to the death of the animal or person concerned. For example, if a person dies from septicaemia, their blood will contain high titres of human pathogens. Similarly, if a farm animal dies from a disease such as Foot and Mouth Disease or Bovine Spongiform Encephalopathy (BSE) the carcass would be potentially contaminated respectively with the virus or prion responsible for these diseases.
There are a number of different sources of such potentially contaminated organic material for which this process of inactivation of pathogens has application: disposal of human remains; disposal of fallen stock such as cattle and sheep; processing of abattoir waste; processing of food waste from production, wholesale and retail sources; disposal of waste from ships and boats; and the disposal of clinical waste from e.g. hospitals.
Alternative processes have been proposed, such as that described in international patent application WO 0140727 in which liquid nitrogen is used to freeze a body prior to mechanical disintegration, and subsequent drying. However, it is well known that liquid nitrogen freezing can actually act to preserve bacteria and other organisms.
An improved process is also described in the applicant's own earlier international patent application WO2008/129322. Whilst this process is effective, its action is most successful against Gram negative bacteria. If it is desired to treat material having a high load of Gram positive bacteria, yeasts, virus and prions, then further improvements are desirable.
It is an object of the invention, therefore, to provide alternative methods for disposal of animal and human bodies using lower energy input, and which result in a microbiologically acceptable material, at least reducing and preferably eliminating virus and prion material.